The design of the structure, shape, and pattern of a tire is to obtain the structure, shape, and pattern of a tire, manufacturing conditions thereof, and the like, which are required to obtain performances of a tire. The performances of the tire is a physical quantity which is obtained by calculation or experiment, or an on-vehicle riding quality evaluation result. A conventional tire design method, such as design of the structure, shape, and pattern of a tire, was realized by a trial-and-error empirical rule obtained by repetitions of experiments and numerical experiments using a calculator. For this reason, the number of trial manufacturing operations and testing operations, which are required for development of a tire, increases greatly, thereby resulting in an increase in developmental costs; further, it was difficult to reduce the period of time for development.
As a means for solving the above-described drawback, there have been proposed techniques for obtaining an optimal solution, for example, a mathematical programming method and an optimization method using a genetic algorithm. A designing method relating to this mathematical programming method has already been proposed by the present applicant in International Publication No. WO94/16877.
Obtaining an optimal solution is analogous to climbing a mountain. At this time, the height of the mountain is related to performance, and therefore, the optimal solution corresponds to the peak of the mountain. When an objective function is simple, a design space (a shape of the mountain) has the shape of a mountain with one peak as shown in FIG. 8, and therefore, the optimal solution can be obtained by an optimization approach based on mathematical programming.
However, when an objective function becomes complex, the design space has many peaks as shown in FIG. 9. For this reason, the optimal solution cannot be obtained by the optimization approach based on mathematical programming. The reason is that, in the optimization approach based on mathematical programming, a peak that was reached first by chance may be mistakenly regarded as the optimal solution.
Although a genetic algorithm has been proposed to solve the above-described problem, it requires a great number of experiments and much time for calculation, and there is also a possibility that calculation may not converge, and so there was a problem in terms of practical use. Namely, when an objective function becomes complex, it was difficult to obtain the optimal solution in a limited period of time.
However, the design development of a tire with a conventional tire design method used was regarded as summarily completed having set a target value for a certain performance and having cleared the target value, and was not provided to obtain the best performance with given resources. Further, this conventional design method was not a method to design an antinomic performance, nor a method to determine the best shape and structure. Moreover, in the conventional design method, development is effected by repeating trial-and-error manufacture and testing, and therefore, this method was very ineffective and cost performance thereof was low.
In view of the above-described circumstances, it is an object of the present invention to provide a tire design method, an optimization analyzing apparatus, and a storage medium in which an optimization analyzing program is stored, which allow design of the best mode of a tire under given conditions and which also allow design and development of the tire to become highly efficient.